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Re: Help with this equation!



Subject:  Re: Help with this equation!
  Date:  Wed, 28 May 1997 17:28:14 +1000 (EST)
  From:  Rodney Davies 3019181 <d3019181-at-bohm.anu.edu.au>
    To:  Tesla List <tesla-at-pupman-dot-com>


Hi Tom,

On Tue, 27 May 1997, Tesla List wrote:

> Subject:      Help with this equation!
>        Date:  Mon, 26 May 1997 21:37:07 -0400
>        From:  Tom Heiber <theiber-at-lonet.ca>
> Organization: Power Surge
>          To:  tesla-at-pupman-dot-com
> 
> 
> This is an equation I got from Bert Pool's file.
> 
>    
> =======================================================================
>     EQUATION 10: CAPACITANCE OF A TOROID
>                                                     ___________________
>                                                    /    2
>          C =(1+ (0.2781 - d2/d1)) x  2.8  x      /  2 pi  (d1-d2)(d2/2)
>                                                /   -------------------
>                                             \/      4 pi
> 
> 
>      C = capacitance in picofarads (+- 5% )
>     d1 = outside diameter of toroid in inches
>     d2 = diameter of cross section (cord) of toroid in inches
> 
>     Equation courtesy of Bert Pool
>    
> =======================================================================
> 
> 
> CAN ANYONE help me solve for D1 as in D1=........
> I have been trying to do this without any results (I suck at math)

Well, I'm not sure if this is right, but still, I couldn't quite solve 
for d1 sorry, but I got this -


2.8^2 x d2^2 = d1[ 0.648474254+(2.8^2 x d2^2) - 
               d1(4 x Pi x C^2 - 0.52794254) ]

Are you trying to construct a toroid to suite a specific capacitance?

You may want to go for 2 equations, one for d1 = ... and another for d2
= ...
, Since the value of d2 may even be dependant on the value of d1.
Usually good to start with an outside diameter and make it's height
1/5th 
of the diam. Doing that should be able to help you get a value for d2...

>From there, just plug in a few different combinations until you get the 
size you require...

Hope this helps a little....

Catchya!
Rod